How fast play from PSRAM chip & how much capacity to use for Audio Raw files??

[charnjit]

I am thinking use of PSRAM chip with teensy 4.1 . before buy chip , i want to ask .,,, if a drum pattern .wav is being played in loop_mode from SD card using [TeensyVariablePlayback] . can i play drum sample together it in polyphony mode by load drum samples .raw files from sd card to PSRAM 8mb.

how fast play accuracy ??? is it fast than direct play .wav from sd card like professional octapad???
how much / how long .raw sample can be load into psram ??? like length & size of sample???
how much time take it in load from sd to psram accord length & size of sample???
when samples are being loaded ,will current running .wav file be affected ??

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PSRAM chip Please check this is it ths one ???

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as shown in this pic......

on which location chip should be solder "A" or "B" ?

if any one of both can be use .
i have to modify .wav files on sd card from pc .. in future if sd card slot missing pins by repetitively remove & insert sd card . can i use any external sd card board with jumper wires to teensy 4.1??
i will place order for PSRAM chip after your suggestion ..
thank you....

 

[PaulStoffregen]

About the PSRAM hardware questions:

As explained on the PJRC page for PSRAM, if using a single 8MB PSRAM chip, it must be soldered to the smaller pads ("A" on your picture). Scroll down to "One PSRAM Chip for 8 MB Memory" for details and a photo (with the ESP PSRAM64H chip).

Please check this is it ths one ???

PJRC currently ships the ApMemory APS6404L_3SQR chip. However, ESP PSRAM64H was previously tested and worked properly.

While I can not say with 100% certainty, my belief is ESP PSRAM64H is probably made by ApMemory (likely the same or very similar part) and simply labeled with ESP's part number.


And about this hardware question:

can i use any external sd card board with jumper wires to teensy 4.1??

Many of these products exist on the market, of varying design and quality. I hope you can understand how this answer can only be generic when you do not mention a specific product with detailed info.

Most of these SD card adaptors are meant to connect by SPI, which uses 4 signals and transfers data with 1 data line. The built in SD socket on Teensy 4.1 uses SDIO which uses 6 signals and transfers data with 4 data lines. You can use SPI adaptors, but they must connect to the SPI pins. SDIO has significantly faster raw speed, though in practice the card's latency is usually the limiting factor.

However, not all SPI adaptors are created equal. Many have buffer chips for compatibility with old 5V Arduino boards. Some of those buffer chips are slow, limiting the clock speed. They can usually be made to work with Teensy, but you may need to configure a slower SPI clock. In Arduino IDE, open File > Examples > SD > SdFat_Usage to see examples of special initialization.

With any high speed signals, best to keep the wires relatively short with GND wires routed close to the clock signal, and ideally with all signal wires having the same physical length.